todo.txt

- on power output
- support for upower-only (and not systemd) systems
    -> "NotifySleep" / "Sleeping" signals?
- test on multiple systems and distributions
- add easy-to-parse output? (shell? json? both?)
- display "Capacity"? (decrease with age)

https://upower.freedesktop.org/docs/Device.html#Device:Online

Target output:

On battery since XXX [monotonic time] (from XXX% ? it's battery specific, move on BAT0 line?)
    + XXX suspended (XXX sleep/resume)
    + XXX halted (XXX stop/start)
Line power unplugged XXX (XXX ago)
BAT0: XXX% [+ other infos of the same line/time]

On line power since XXX (XXX)[simple wall time]
BAT0: XXX% [+ other infos of the same line/time]
    charging since XXX [monotonic] from XXX%
    + XXX suspended (XXX sleep/resume)
    + XXX halted (XXX stop/start)
BAT1: XXX% [+ other infos of the same line/time]
    charged in XXX from XXX% [monotonic too?]
    + XXX suspended (XXX sleep/resume)
    + XXX halted (XXX stop/start)